C 0 2 Studies
Recently, long-term energy projections have become an essential part of global economic and social planning because of the long lead times of new energy technologies' penetration and their high capital intensities. Several years ago the long-term approach t o energy projections was stressed. At that time it was discovered that increasing amounts of atmospheric COz concentrations were causing global warming; atmospheric C 0 2 concentrations to a large extent are caused by fossil fuels use. For this reason global, long-term energy projections are again the focus of many research studies being carried out over recent years.
There is a multitude of global, long-term energy projections published worldwide. Most appeared in the late 1970s and early 1980s, and a new wave occurred in the late 19806, when the threat of global warming started t o be considered a real and serious global problem. These studies use different assumptions, methodological approaches, and time periods and are based on different sets of input data: global/regional economic and population growth, costs and efficiencies of energy technologies evaluations, availability of conventional and renewable energy sources, and so on. Strictly speaking, the diverse features of these studies makes comparisons practically impossible. Here we will attempt to analyze the quantitative results of a few selected studies without trying t o clarify why and how such results came about. Such a simplified approach makes it possible to notice the evolution of long-term energy projections over time.
To review global energy/COz projections, we use original publications as well as summaries of global/regional studies presented a t IIASA's International Energy Workshop in June 1989.
We have chosen the following studies (in order of their appearance) for further analysis from a long list of available publications:
Nordhaus, W.D., Strategies for the Control of Carbon Dioxide (1977).
WCG (Working Consulting Group) of the President of the USSR Academy of Sci- ences, Long-Term Global Energy Projections, Moscow (1978)(in Russian).
Colombo, U. and 0. Bernardini, A Low Energy Growth Scenario and the Perspec- tives for Western Europe, Report prepared for the Commission of the European Communities, Panel on Low Energy Growth (1979).
Rotty, R. and G. Harland, Constraints on Carbon Dioxide Production from Fossil Fuels Use (1980).
Hiifele, W. et al., Energy in a Finite World: A Global Systems Analysis. Report by the Energy Systems Program of the International Institute for Applied Systems Analysis. Cambridge, Mass: Ballinger (1981).
Lovins, A., L. Lovins, F. Krause, and F. Bach, Energy Strategies for Low Climatic Risk. Report t o the German Federal Environment Agency (1981).
Nordhaus, W. and G. Yohe, Future Paths of Energy and Carbon Dioxide Emis- eion. In Changing Climate, Report of the Carbon Dioxide Assessment Committee.
Washington, DC: National Academy Press (1983).
Edmonds, J. and J. Reilly, A Long-Term Global Energy-Economic Model of Carbon Dioxide Release from Fossil Fuel Use. Energy Economist 5:74-88 (1983).
Rose, D., M. Miller, and C. Agnew, Global Energy Futures and COz-Induced Cli- matic Change. Report MITEL 83-015. Cambridge, Mass. (1983).
Goldemberg, J., T. Johansson, A. Reddy, and R. Williams, An End-Use Oriented Global Energy Strategy. Annual Review of Energy 10:613-688 (1985).
Edmonds, J. and J. Reilly, Global Energy: Assessing the Futum. New York: Oxford (1985).
F'risch, J .-R., Long-Term Energy Alternatives t o Hydrocarbons, Presented at the 12th World Petroleum Congress, Houston, TX (1987).
AMOCO Corporation, Lower and Upper Price Cases, Presented at the International Energy Workshop, IIASA, Laxenburg, Austria, June (1989).
Centre for International Energy Studies, Erasmus University, High, Low, and Mid- Point Demand Growth, Presented a t the International Energy Workshop, IIASA, Laxenburg, Austria, June (1989).
Ashby, A. and D. Dreyfus, Global Outlook for Service Sector Energy Requirements, Presented a t the International Energy Workshop, IIASA, Laxenburg, Austria, June (1989).
14th Congress of the World Energy Conference. Conservation and Studies Commit- tee, World Energy Horizons 2000-2020, Paris (1989).
Hlifele, W., Energy Systems Under Stress, Invited paper, 14th World Energy Con- ference, September 1989.
Starr, C. and M. Searl, Global Projections of Energy and Electricity. American Power Conference, Annual Meeting, Chicago, Ill., April (1989).
Sinyak, Y., Global Energy/COz Projections, Unpublished report, IIASA, Laxenburg, Austria (1990).
US EPA and US DOE, Atmospheric Stabilization F'ramework (1990).
F'rom a methodological viewpoint, these studies can be divided into four groups:
1. Studies based on reasonable judgments and assumptions without the application of math- ematical models and tools or detailed calculations [see, for example Hafele (1989)l.
2. Studies with collective views based on initial assumptions and an iterative process of finding a consensus. (A good example of such an approach is the study prepared for the
14th World Energy Conference by a group of experts with Dr. J.-R. F'risch as Project Director. An extensive information exchange between experts and the central team was used t o produce final, consistent results.)
3. Studies directed a t the detailed analysis of energy end-consumers and assessments of effi- ciencies of new energy technologies, using a normative approach t o global energy problems [see, Goldemberg et al. (1985) and Lovins et al. (1981)l.
4. Studies with modeling approaches for solving global energy problems
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from simplified models of energy/economy interactions [WCG (1978) and Sinyak (1990)l t o complicated sets of mathematical optimization models [Hifele et al. (1981) or Rotty and Harland (1980)l t o complex computer modeling systems using simulation procedures (Edmonds and Reilly, 1985).The analysis of available studies shows that the majority of the projections predict a further growth in global energy demand ( Table 9), but several prognoses deviate from this overall trend:
Goldemberg et al. (1985), for example, assume an energy demand stabilization until 2020, Lovins et al. (1981) are convinced that global energy demand could even be reduced t o early 1980 levels by the year 2030.
It is interesting t o see the evolution of projections. The average global energy demand esti- mate in 200 pre-1985 studies is equal t o 17 billion tce annually, whereas after 1985 the average estimate is already remarkably lower: only 13 billion tce. The same trend but with pronounced deviations downward can be seen for subsequent time periods: the average estimate of pre-1985 studies for 2025 is above 25 billion tce as compared with only 17 billion tce estimated in studies
Table 9: World energy demand projections (billion tce).
Reference 2020- 2030- 2050-
Sources 2000 2010 2030 2040 2060
WCG (1978) 18.3-21.2 30.9-38.3 43-55
Colombo and Bernardini (1979) 15.4
Hiifele et al. (1981)
Sinyak (1990) 13.7-14.1 17.1-20.0 20.0-25.0 21.0-32.0
US EPA/DOE (1990) 18.2 17.0-23.0
conducted after 1985. Even more striking is the reduction in global energy-demand assessments for the middle of next century: about 50 billion tce for 2050 in pre-1985 studies as compared with 25 to 27 billion tce for 2060 in studies published after 1985. All these changes indicate a drastic shift to assessing the role future energy systems will play and to using the huge energy conservation potential that exists in all economic sectors of developed and developing countries.
It has become evident that energy savings are real long-term factors in energy systems develop- ment which provide further economic growth with minimal risks to the environment, mankind, and resource exhaustion and, moreover, with less capital and operation and maintenance costs.
Most interesting is the comparison of three studies: Sinyak (1990); Edmonds and Reilly (1985); and F'risch (1987). All of them have almost the same time horizon; deal with global/
regional aspects of energy demand evolution; and, moreover, consider energy demand not only in total but by primary energy forms. Furthermore, they try t o link energy systems development t o global climate changes resulting from increased C 0 2 concentrations.
The projections show a steady growth in global energy demand until the middle of the next century but with different growth rates. According t o WEC-14 projections, annual growth rates will decline from 1.5% in 2000-2020 t o 0.7% in 2040-2060. Edmonds and M y (1985) assume rather high annual growth rates for primary energy demand during the first half of the next century (2.5% per year), which result in an overestimation of primary energy demand and COz emissions.
Concerning the different primary energy demand forms, there are large discrepancies among the different projections (Table 10). Edmonds and Reilly (1985) expect a doubling of crude oil production from 2000 t o 2050, reaching 10.2 billion tce (more than 7 billion toe), including un- conventional liquid fuels resources like oil shales, heavy oils but without synthetic oils produced from coal. According t o projections by F'risch (1987), global crude oil production will reach its peak in 2000 and then will slightly decrease until 2060. Projections by Sinyak (1990) assume a
sharp reduction in crude oil production in case of regulatory constraints of strategies directed t o a delay in global warming, and a stabilization over the whole period if the consequences of global warming turn out t o be less severe and no special regulations are applied. The magnitude of existing crude oil projections can be explained by the different treatment of unconventional oil resources in the studies. For example, Edmonds and Reilly (1985) assume that twethirds of the crude oil production in 2050 will be from unconventional sources with lower costs than in the case of synthetic oils production from coal.
Just the opposite is the case with natural gas production. According t o Edmonds and Reilly (1985), after 2025 natural gas demand will decline because of the rapid exhaustion of conventional natural gas resources which will be replaced a t a very slow pace by unconventional resources with extraction costs much higher than that of substitute natural gas production from coal. F'risch (1987) assumes a steady growth in natural gas production until 2060. Sinyak's (1990) projections support Edmonds and Reilly's projections and F'risch's projections: with minimal fossil fuel consumption (limited fossil fuels use options) they are close t o Edmonds and Reilly's projections; with maximal fossil fuels use, they are close t o the projections of F'risch (nuclear moratorium or nuclear reductions options).
The situation of coal prospects remains very uncertain. It is quite evident that in the case of restrictions for fossil fuel consumption, because of the many environmental, economic, and societal factors, the use of coal has t o decline. If nuclear energy, in turn, is constrained or substantially reduced, then only coal will be able t o
fill
the gap in expected primary energy demand which will be followed by increased C 0 2 emissions. Therefore, depending on initial assumptions, the long-term coal projections could differ by an order of magnitude. Coal's share (including biomass) is, according t o Edmonds and Reilly (1985), a t the highest level in 2050 (45%), with coal production of more than 25 million tce (almost eight times more than in the mid-1980s). They assume that after 2025 synthetic liquids and gaseous fuels from coal will vastly expand, and according t o their estimates one-third of the coal produced will be used for this purpose. Meanwhile, the synfuels from coal have ever higher C 0 2 emissions per unit of energy than those produced by liquid gaseous fuels from natural sources (e.g., three times more than that for natural gas).Assessments of the future role of nuclear energy show the biggest deviations. Edmonds and Reilly's projections for 2050 are almost three times that of F'risch's but very dose t o the level predicted in Sinyak's limited fossil fuels use option in the base scenario. However, this level could be reduced by half in the case of enhanced energy saving accompanied by global-warming regulations. Edmonds and Reilly build their projections on the assumption of a higher economic efficiency for nuclear energy together with growing crude oil and natural gas prices and far- reaching consequences of environmental pollution. They predict a 5.6% growth rate for nuclear energy between 2000 and 2025 and 3.4% between 2025 and 2050. But they could not account for the consequences of Chernobyl and the resulting negative public opinion for nuclear energy.
This is the main reason for their overestimates in nuclear projections. At the same time it is necessary t o understand that without nuclear energy the global-warming problem can hardly be solved in the next century, even with enhanced energy-savings policies. This position is also supported by the World Energy Conference (WEC, 1989), HZele (1989), and many others.
The future role of renewable energy sources is in all studies evaluated as modest, although the absolute volume of this energy form will increase by several factors. Only Sinyak (1990) projects the share of renewables t o be a t a very high level (maybe even too high!) in the limited fossil fuels use scenarios.
In summary, one could point out some common tendencies in energy systems development concerning energy demand growth, conventional crude oil and natural gas resources exhaustion, production of unconventional crude oil, and, t o a lesser extent, unconventional gas production and the penetration of nuclear and renewable energy sources in the global energy balance.
However, the future structure of primary energy supply and production levels of different energy forms remains very uncertain, which shows that further research in this field in necessary.
Table 10. World energy supply by energy sources (billion tce).
Resource Reference 1985 2000 2020-2030 2030-2040 2050-2060
Crude
In recent projections, many authors consider C 0 2 emissions as the major element in ex- pected global warming. First, burning fossil fuels to provide society with useful energy forms produces large quantities of C 0 2 released into the atmosphere. Second, C 0 2 emissions and their related global-warming effect have a global character unlike many other air pollutants with only regional/local impacts. Third, the negative consequences of global warming might be noticed Boon (within the next decades: the lifetime of energy equipment built now). All this makes the C 0 2 problem an essential element of global energy projections.
Many studies forecast a steady increase in global C 0 2 emissions (see again Table 10). How- ever, a few projections predict reductions in C 0 2 emissions: for example, Rotmans et al. (1989) show that annual C 0 2 emissions could be reduced by a factor of two by 2050 as compared with today'e levels.[5] The dynamics of this indicator provides two distinct periods: the f i s t from 2020 t o 2025, when the majority of projections expect modest growth, and the eecond after 2025, when a sharp growth occurs because of changes in primary energy mix connected t o the higher use of coal for synthetic fuel production as well as to high levels of crude oil production from oil shales, both of which are accompanied with high COz emissions. The diverging C 0 2 emission assessments in the studies can be explained by the different evaluations of specific emissions caused by burning fossil fuels.
When calculating C 0 2 concentrations in the atmosphere, many studies use different assess- ments of the share remaining in the atmosphere after part of the C 0 2 is absorbed by the oceans.
This share ranges from 40% t o 70% (naturally, the wide magnitude of estimates produced highly different results). The expected C 0 2 emissions are shown in Table 11.
Table 11: Expected annual C 0 2 emissions (billion C/yr).
Reference 2020- 2030- 2050-
'Including other COz murcca besidca foseil fuels m d other trace gases.
All
studies indicate increasing C 0 2 concentrations until the middle of next century (see Table 12), but it will be hardly double that of the preindustrial period. Sinyak (1990) predicts increasing C 0 2 concentration levels up to 460-550 ppm by 2060 (this only accounts for burning fossil fuels and not for anthropogenic and other natural factors). Rotmans et al. (1989) show a possible stabilization of C 0 2 concentrations during the next century if drastic preventive measures are initiated immediately t o reduce fossil fuels use and to control other emissions from trace gases.In conclusion, it is necessary t o note that there are common trends in all studies for fu- ture development. But a t present, differences in numeric results are still significant. These differences demand additonal efforts in energy/C02 research with improvements in projection methodologies and in studying the causes for global warming (either natural or anthropogenic).
Table 12: COz concentration projections (ppm).
Reference 2020- 2030-
Sources 1985 2000 2030 2040 2050 2060
Edmonds and Reilly (1985) 380 445 575
Hiifele et al. (1981) 350-370 410-490
Minzer (1989) 350-380' 360-490' 400-630'
Rotmans et al. (1989) 340 360' 370-530'
Sinyak (1990) 373 410420 440-480 460-550
WEC-14 (1989) 348 372-377 395-410 423-456
Haele (1989) 410 440 460 470 475
'Including C02 sourcea besides fossil fuels and other trace gases.
6
Conclusions
1. Energy as a driving force of social and technological progress will keep its leading role among major global problems during the 21st century. This calls for necessary and expedi- ent elaborations of long-term energy projections. The many forms of energy development, uncertainties in input assumptions and parameters, and differences in socio-philosophical concepts of societal development explain the diversity in approaches to solving global en- ergy problems and periodic reevaluations of long-term forecasts.
2. Today's energy systems have entered a period of transition from systems based on ex- haustible fossil fuels resources to systems based on practically inexhaustible resources (nuclear fission and fusion, renewables). The duration of this transition period will de- pend on many factors. The main factors certainly are the significance of climatic and environmental degradations associated with the different energy systems and technologies and the social costs of various energy sources. The global-warming issued could speed up the pace of this transition.
3. The next decades (at least until the middle of the next century) of global energy systems development will be characterized by the following:
Further energy demand growth (mainly in socialist and developing countries).
Growing importance of energy conservation and savings in all areas of energy pro- duction and consumption.
Severe limitations in nuclear energy development (especially during the next couple of decades) until new generations of nuclear reactors are installed with much higher safety rates.
Limited contribution of renewable energy sources t o the global energy balance which is due to their unfavorable economics, often negative impacts, and unreliability.
Fossil fuel will keep its leading role in the global energy supply from the viewpoint of resources availability and production costs, although ecological and climatic factors will greatly influence its future use.
The influence of ecological and climatic factors in compiling energy strategies will increase, while the impact of political and economic factors, presently dominating the energy-related decision-making processes, will decrease.
4. In light of these anticipated tendencies, global energy demand might increase from the current levels of 11.5 to 13-14 billion tce in 2000 and up to 20-30 billion tce in 2060.
Moreover, energy demand in developed countries will remain stable or even start to decline
after that period (it is quite probable that the absolute level of energy demand in some developed countries will start to decrease in the near future). The largest growth in global energy demand will take place in developing countries (including China and other socialist countries). The expected energy demand growth in developing countries with market economies will be six- to tenfold and in socialist countries 1.7-2.2 times that of mid-1980 levels. At the same time the share of developing countries with market economies will increase from 11.5% in 1980 t o 42%-52% in 2060 and the developed countries' share, which now exceeds 50%, will decrease t o 16%-12% in 2060. Such drastic changes in the global energy demand structure indicate the shift of global, energy-related problems t o the regions of developing countries in the coming decades. This will be followed by new "hotn points in solving global, energy supply problems if reasonable measures are not taken in time.
5. The primary energy supply structure in the next 70 t o 80 years will be strongly depen- dent upon the applied energy development strategies. In the business-as-usual scenario (without any constraints on fossil fuels or nuclear energy), coal production will increase t o 5-10 billion tce annually until the end of the projection period, conventional crude oil t o 3.2-4.2 billion tce, and natural gas to 3.4-4.8 billion tce. The total share of nuclear and renewable energy will reach 40%-45%. However, in the case of the global-warming preven- tion strategy, the share of fossil fuels must be substantially reduced (in our assessments t o 25%-28% in 2060), with coal and crude oil production - because of C 0 2 emissions - the global climate, it is unlikely that increasing atmospheric C 0 2 concentrations can be avoided during the period under consideration (the most we can expect is a possible delay in global warming for a couple of decades). Parallel to these measures other efforts have t o be taken. (First of all intensive global reforestation and reduction of other trace gase emissions, which contribute up t o 50% to global warming.) Broad-scale investigations on the phenomenon of global warming and its consequences must be started, and preventive measures must be evaluated in order to choose the optimal strategy for social and economic development worldwide. The climate-change issues should be treated as a real and essential global problem that requires the collective efforts by all nations looking for the optimal path t o global/regional energy development (especially for the next several decades in view of the high uncertainty and remote consequences).
5. The primary energy supply structure in the next 70 t o 80 years will be strongly depen- dent upon the applied energy development strategies. In the business-as-usual scenario (without any constraints on fossil fuels or nuclear energy), coal production will increase t o 5-10 billion tce annually until the end of the projection period, conventional crude oil t o 3.2-4.2 billion tce, and natural gas to 3.4-4.8 billion tce. The total share of nuclear and renewable energy will reach 40%-45%. However, in the case of the global-warming preven- tion strategy, the share of fossil fuels must be substantially reduced (in our assessments t o 25%-28% in 2060), with coal and crude oil production - because of C 0 2 emissions - the global climate, it is unlikely that increasing atmospheric C 0 2 concentrations can be avoided during the period under consideration (the most we can expect is a possible delay in global warming for a couple of decades). Parallel to these measures other efforts have t o be taken. (First of all intensive global reforestation and reduction of other trace gase emissions, which contribute up t o 50% to global warming.) Broad-scale investigations on the phenomenon of global warming and its consequences must be started, and preventive measures must be evaluated in order to choose the optimal strategy for social and economic development worldwide. The climate-change issues should be treated as a real and essential global problem that requires the collective efforts by all nations looking for the optimal path t o global/regional energy development (especially for the next several decades in view of the high uncertainty and remote consequences).